Process for bleaching tobacco



Patented Mar. 3, 1942 PROCESS FOR BLEACHING TOBACCO Hermann Baler,Frankfort-on-the-Main, Germany, assignor to Deutsche Gold und .SilberScheideanstalt vormals Roessler, Frankforton-the-Main, Germany, acorporation of Germany No Drawing. Application May 24, 1939, Serial No.275,540. In Germany January 28, 1935 6 Claims. (Cl. 131-142) Thisinvention relates to the bleaching of tobacco and, more especially, to aprocess for bleaching tobacco utilizing hydrogen peroxide. Hydrogenperoxide has been found effective not only for improving the color ofthe tobacco but I also for rendering it milder. This application is acontinuation-in-part of my copending appli-' and are now employed in thetreatment of tobacco with hydrogen peroxide. One of these processes isthe well-knowndipping process for refining tobacco in which the tobaccois soaked for a certain period of time in an alkaline solution ofhydrogen peroxide. Subsequent to this soaking it is removed and dried.Other methods for treating tobacco involve a spraying process.

In the spraying process the tobacco may be treated with an alkaline,preferably ammoniacal,

solution of hydrogen peroxide which is applied to the leaf or cuttobacco through suitable nozzles. A variant of this process is theammonia vapor process in which the tobacco is first sprayed with asolution of hydrogen peroxide and then treated with ammonia vapor. Thelatter procedure has the distinct advantage that after completion of thebleaching the tobacco is free from hydrogen peroxide, whereas in otherprocesses undecomposed hydrogen peroxide remains on the tobacco.

However, the use of a process in which the tobacco is subjected to theaction of ammonia vapor requires a relatively complex and expensiveapparatus, and its use in many factories would necessitate the scrappingof old equipment and itsreplacement by new. For these reasons it hasbeen customary in the past to employ one of the other processes which donot require additional plant expense. Indeed the industry has usuallypreferred the simple spraying process, using an ammoniacal solution ofhydrogen peroxide, chiefly for the reason that it may be utilizedwithout materially changing the apparatus now installed in thefactories, engaged in the processing of tobacco.

After the tobacco is treated with hydrogen peroxide utilizing thespraying method previously referred to, it has been found that some ofthe hydrogen peroxide still remains undecomposed in or on the tobacco.Just after the treatment is completed the tobacco still possesses itsfull aroma and is very pleasant and mild. However, during thestorageperiod which necessarily occurs after the treatment much of the aroma islost; and the flavor becomes very much less pleasant when the tobaccoissmoked. I

The invention with which this application is concerned is based on thediscovery that during storage the quality of the tobacco is impaired bythe residual hydrogen peroxide which remains in the undecomposed stateon the tobacco at the conclusion of its treatment with the bleaching andrefining agent. Research has revealed that the tobacco is capable ofchemically combining with the hydrogen peroxide, its ability to do thisvarying, however, with different types of tobacco.

The ability to combine chemically with the peroxide is much morepronounced in tobaccos of relatively high aroma than in those whichpossess a poor aroma. During the storage period the residual hydrogenperoxide gradually decreases,

and after a certain period of time no residual hydrogen peroxideremains. The period of time necessary for complete decomposition of theundecomposed hydrogen peroxide depends essentially on the quality of thetobacco. When a mixture of 50% domestic and 50% foreign tobacco isprepared it has been found that the tobacco must be stored from 4 to 10days before it is completely free from hydrogen peroxide and of constantchemical composition.

I have now found that all of these changes in the chemicalcharacteristics of the tobacco, with consequent deterioration to itsquality, occurring during the storage period, may be avoided if thetobacco is subjected to the action of an agent which causesdecomposition of the residual hydrogen peroxide. These agents may beapplied at the conclusion of the hydrogen peroxide treatment step or maybe added to the tobacco prior to contacting the tobacco with thesolution of hydrogen peroxide. The residual hydrogen peroxide mayconveniently be removed either by chemical action such as by reductionor by the action of catalysts. As an agent to react with the hydrogenperoxide and destroy the residual peroxide,

sulfurous acid, salts of sulfurous acid such as potassium or sodiumbisulflte, a metal permanganate such as sodium or potassiumpermanganate, or glucose (grape sugar) may be used. The treatment tochemically remove remaining peroxide is preferably carried out byspraying the tobacco which has been treated with the hydrogen peroxidewith a dilute solution of the treating agent. i

As the agent for destroying residual hydrogen peroxide I prefer to usethe reducing agent glucose, in dilute solution, and this sugar solutionmay be readily sprayed by means of a nozzle or any similar apparatusdirectly on the tobacco after the peroxide treatment. As an alternativemethod of applying the glucose, it may be added directly to the tobaccosauce so that the usual tobacco saucing treatment and the treatment withglucose are carried out in a single operation. These customary tobaccosauces contain or comprise the well known substances which improve thetaste or the smell of the tobacco. Such substances are for instanceextracts. of currants, cinnamon, aniseed, sugar, glycerine, hygroscopicsubstances such as calcium chloride, also substances with a disinfectingeffect, uch as benzoic acid and the like.

After tobacco has been subjected to the action of hydrogen peroxide, theadhering undecomposed hydrogen peroxide may also be destroyed bycontacting the tobacco with certain substances which act catalyticallyto decompose hydrogen peroxide. The same effect may be obtained if thesesubstances are added to the tobacco before the tobacco is treated withhydrogen peroxide, as for example, before the tobacco is treated withthe tobacco sauce. Any suitable decomposition catalyst for hydrogenperoxide may be utilized and I have found particularly useful cobaltsalts, nickel salts, and iron salts. Certain organic catalysts may alsobe used in the removal of residual hydrogen peroxide, as mayultra-violet light or ozone, both of which also operate to remove ordecompose the hydrogen peroxide remaining in the treated tobacco.

As an alternative method of carrying out the process, there may be addedto the tobacco, before the tobaccois treated with hydrogen perom'de, amaterial which will react chemically with the hydrogen peroxide. Thetobacco may then be contacted with the solution of hydrogen peroxide andat the conclusion of the treatment is substantially free fromundecomposed hydrogen peroxide, since the residual peroxide is destroyedby chemical action with the materials previously added to the tobacco.The tobacco may then be further treated with a substance eifectingdecomposition of any excess or residual hydrogen peroxide remaining,which substance may conveniently be added in conjunction with thetobacco sauce, applied to the tobacco in the usual saucing treatment.

By the process described in which the residual hydrogen peroxide isremoved from the tobacco after the latter has been subjected to refiningaction of this oxygen-evolving compound I have found that raw,unpleasant tobacco is transformed into tobacco of a. much milder quality"which is more desirable for smoking purposes.

At the same time the lightened color, attributable to the bleachingaction of hydrogen peroxide, is much preferred by the generalsmoking'public.

By the use of the lighter, milder tobacco prepared in accordance with myrocess, it has been found that the expensive foreign tobacco now blended'with domestic tobacco in the preparation of I have given asillustrative which will neverthe-' less still fall within the scope ofmy invention. The various details given are to be considered asillustrative and not restrictive and the scope of the invention is to bedetermined solely in accordance with the appended claims.

I claim:-

1. A process for refining tobacco which comprises subjecting the tobaccoto the action of hydrogen peroxide and subsequently contacting saidtobacco witha decomposition catalyst for decomposing hydrogen peroxidein order to destroy hydrogen peroxide remaining undecomposed on saidtobacco. 2. A process for refining tobacco which comprises adding tosaid tobacco a substance which acts catalytically to decompose hydrogenperoxid'e and then contacting said tobacco with a solution of hydrogenperoxide, whereby the tobacco at the conclusion of the treatment issubstantially free from undecomposed hydrogen peroxide.

3. A process for refining tobacco which comprises adding to said tobaccoa material which reacts chemically with hydrogen peroxide and thencontacting said tobacco with a solution of hydrogen peroxide, wherebythe tobacco at the conclusion of the treatment is substantially freefrom undecomposed hydrogen peroxide.

4. A process for refining tobacco which comprises adding to said tobaccoa material which reacts chemically with hydrogen peroxide, contactingsaid tobacco with a solution of hydrogen peroxide, whereby the tobaccoat the conclusion of the treatment is substantially free fromundecomposed hydrogen peroxide and further adding a substance whicheffects decomposition of the excess of hydrogen peroxide in conjunctionwith the tobacco sauce subsequently applied to the tobacco. p

5. A process for refining tobacco which comprises treating said tobaccowith hydrogen peroxide in the presence of an agent for decomposinghydrogen peroxide, whereby the tobacco, at the conclusion of thetreatment, is substantially free from undecomposedhydrogen peroxide.

6. A process for refining tobacco which comprises treating said tobaccowith hydrogen perox- HERMANN BAIER.

